JP5292023B2 - Polymerization inhibiting method and polymerization inhibitor - Google Patents

Description

The present invention relates to a use of a salicylic acid hydrazide or a derivative thereof having water-solubility, low colorability and excellent safety, and a polymerization inhibitor . More specifically, the present invention relates to a method for use in inhibiting polymerization of salicylic acid hydrazide or various monomers thereof, which is water-soluble, low-coloring and excellent in safety, and a polymerization inhibitor containing them .

  Conventionally, phenolic compounds and amine compounds are widely used as water-soluble polymerization inhibitors and antioxidants. For example, hydroquinone and methoquinone are widely used. As water-soluble polymerization inhibitors, those derived from natural products such as citric acid and ascorbic acid, and inorganic salts such as sodium nitrite and sodium iodide are also used.

  In Patent Document 1, for example, water-soluble radical scavengers such as inorganic salts such as sulfites and metal salts such as ascorbic acid and citric acid are used as water-soluble polymerization inhibitors in (meth) acrylic acid esters. It has been proposed to add. Patent Document 2 proposes the use of ascorbic acid, sodium iodide or the like as a water-soluble polymerization inhibitor added to glycidyl methacrylate. On the other hand, Patent Document 3 discloses the use of ascorbic acid or a salt thereof, citric acid or a salt thereof as an antioxidant for fats and oils or oil-containing foods. However, none of the documents pays attention to the low coloring property.

  By the way, the polymerization inhibitor and inorganic salts derived from natural products are not necessarily sufficient in the polymerization inhibitory effect and often cannot exhibit the desired effect. In addition, when a phenolic compound or an amine compound is used as a polymerization inhibitor, these additives often have a coloring phenomenon when manifesting the effect, and this coloring often causes coloring of the added substrate. There was a problem. For example, in a vehicle transparent member or a transparent sheet member that requires a high degree of transparency, coloring must be avoided, and in lenses, prisms, optical disks, and sheets that are optical equipment members Is required to have hue stability. Similarly, highly water-absorbing resin used for semiconductor members, electronic materials, adhesives, adhesives, paper diapers and absorbent pads, waterproof and rust-preventing spray materials, inks, paints such as water-based paints, fibers, paints, resins Even in the case of fiber modifiers, there is a strong demand for the appearance of a low color polymerization inhibitor. Currently, coloring is prevented by separately adding a coloring inhibitor in addition to the polymerization inhibitor.

  N-nitroso-N-phenylhydroxylamine ammonium salt (cuperon) is mentioned as a water-soluble and low-coloring polymerization inhibitor. However, it is self-reactive and explosive and requires storage at low temperatures. In addition, use is limited because of suspected carcinogenicity. Therefore, a polymerization inhibitor that is water-soluble, has low coloring properties and is excellent in safety is awaited. In particular, various paints in which the use of organic solvents is not favored or restricted, especially household paints, are currently widely used based on water, but there are currently no effective polymerization inhibitors. It is.

JP 2007-70624 A JP 2006-151975 A JP 2007-185138 A

An object of the present invention is to provide a polymerization inhibitor that does not substantially cause a coloring phenomenon over time, is water-soluble and has excellent safety, and a polymerization suppression method using the polymerization inhibitor. It is .

  As a result of extensive research, the present inventors have found that a specific salicylic acid hydrazide or derivative thereof, which is sometimes used as a lubricant stabilizer, can achieve the above-mentioned object, and has completed the present invention. is there.

（式（１）中、Ｚは−ＮＨＲ_１又は−Ｎ＝ＣＲ_２Ｒ_３で表され、そして、Ｒ_１、Ｒ_２、Ｒ_３の何れも、水素又は炭素数１〜６の分岐していても良い飽和アルキル基を示す。）であるサリチル酸ヒドラジド又はその誘導体を、（メタ）アクリル酸、そのエステル、若しくは、その塩であるモノマー、オリゴマー等の部分重合体の重合抑制のために用いること、及びそれを用いた重合抑制剤に関する。本発明に係るサリチル酸ヒドラジド又はその誘導体は、水溶性であり、かつ基材の着色を抑制でき、加えて、安全性の面でも問題の少ない物質である。なお、Ｒ_１で表される炭素数１〜６の分岐していても良い飽和アルキル基としては、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、セカンダリーブチル基、ターシャリーブチル基、ペンチル基、イソペンチル基、セカンダリーペンチル基、ヘキシル基、イソヘキシル基、セカンダリーヘキシル基が挙げられる。また、Ｒ₂、Ｒ₃は、何れか一方がメチル基のとき、他方の炭素数１〜４の分岐していても良い飽和アルキル基としては、プロピル基、イソプロピル基、ブチル基、イソブチル基、セカンダリーブチル基、ターシャリーブチル基が挙げられる。 That is, the present invention provides the following formula:

(In the formula (1), Z is represented by —NHR ₁ or —N═CR ₂ R ₃ , and each of R ₁ , R ₂ , and R ₃ is hydrogen or branched from 1 to 6 carbon atoms. A salicylic acid hydrazide or a derivative thereof, which is a good saturated alkyl group.) (Meth) acrylic acid, an ester thereof, a salt thereof, a monomer, an oligomer or the like is used for polymerization inhibition . And a polymerization inhibitor using the same . The salicylic acid hydrazide or a derivative thereof according to the present invention is water-soluble and can suppress coloring of the base material, and in addition, is a substance with few problems in terms of safety. The saturated alkyl group having 1 to 6 carbon atoms represented by R ₁ may be a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, or a tertiary group. Examples include a butyl group, a pentyl group, an isopentyl group, a secondary pentyl group, a hexyl group, an isohexyl group, and a secondary hexyl group. In addition, when any one of R ₂ and R ₃ is a methyl group, the other saturated alkyl group having 1 to 4 carbon atoms may be a propyl group, an isopropyl group, a butyl group, an isobutyl group, A secondary butyl group and a tertiary butyl group are mentioned.

Among them, in the salicylic acid hydrazide represented by the above formula (1) or a derivative thereof, R ₁ in the formula is hydrogen or a saturated alkyl group having 1 to 6 carbon atoms which may be branched, and R ₂ and R ₃ are either Desirable is salicylic acid hydrazide or a derivative thereof, one of which is a methyl group and the other is a saturated alkyl group having 1 to 4 carbon atoms.

Further, among salicylic acid hydrazides or derivatives thereof, salicylic acid hydrazide (hereinafter referred to as compound 1), N ′ -(1-methylethylidene) salicylic acid hydrazide (referred to as compound 2), N ′-(1-isobutylethylidene) salicylic acid hydrazide (compound 3) N ′-(1-methylethyl) salicylic acid hydrazide (referred to as compound 4) and N ′-(1-isobutylethyl) salicylic acid hydrazide (referred to as compound 5) are preferably used. Of course, these may be used alone or in combination.

  A monomer to which salicylic acid hydrazide or a derivative thereof is added or a partial polymer thereof is (meth) acrylic acid, an ester or a salt thereof, and is preferably 5 to 1000 ppm with respect to the monomer or the partial polymer. Can be obtained by adding 10 to 500 ppm in order to obtain a low coloring polymerization inhibitory effect.

By using the above-mentioned salicylic acid hydrazide or a derivative thereof in the polymerization inhibition method and polymerization inhibitor of the present invention, coloration due to change over time or heat does not substantially occur, or coloration that causes no problem in actual use is recognized. Therefore, it can be suitably used for applications where coloring is not preferred .

  Production of salicylic acid hydrazide or a derivative thereof used in the present invention can be carried out, for example, by the method disclosed in Japanese Patent Application Laid-Open No. 2007-161996 by the present inventors. However, it goes without saying that the salicylic acid hydrazide or derivative thereof used in the present invention can be produced by methods other than those described above.

The salicylic acid hydrazide or derivative thereof used in the present invention is used for inhibiting polymerization of various products including a monomer such as (meth) acrylic acid, an ester thereof, or a salt thereof, or a partial polymer (oligomer) thereof. Is possible. For example, household water-based paint, adhesive, ink, paint, adhesive, water tank, vending machine front plate, vehicle transparent member, transparent sheet member, optical device member lens, prism, optical disk, sheet, Examples thereof include raw materials monomers such as semiconductor members, electronic materials, superabsorbent resins, fibers, paints, resins, and fiber modifiers. In the polymerization inhibiting method according to the present invention, the above-described salicylic acid hydrazide or a derivative thereof may be added in an amount of 5 to 1000 ppm, preferably 10 to 500 ppm, based on the monomer or a partial polymer thereof.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, of course, this invention is not limited to these Examples.

  The salicylic hydrazide or derivative thereof used in the present invention is water-soluble. As an example, the solubility of salicylic acid hydrazide (Compound 1) in water is shown in Table 1. In addition, p-methoxyphenol (MQ), hydroquinone (HQ), methyl hydroquinone (MH), tertiary butyl hydroquinone (TBH), 2,2′-, which may be currently used as a water-soluble polymerization inhibitor. The solubility of methylene-bis (4-methyl-6-tertiarybutylphenol) (MBP) and 2,6-di-t-dibutylhydroxytoluene (BHT) in water is also shown.

(Polymerization inhibition test)
The test used the TG-DTA apparatus (Rigaku TG 8120). MQ contained in commercial acrylic acid was removed by distillation to prepare acrylic acid for use in this test. A mixture of acrylic acid not containing MQ and water prepared in a 2: 1 ratio is used as a test solution. As various polymerization inhibitors, five compounds of the above-mentioned compounds 1 to 5 which are representative salicylic acid hydrazides or derivatives thereof according to the present invention, and methylhydroquinone and 10 ppm of p-methoxyphenol as comparative examples were added to the test solution, respectively, and TG-DTA Place in a sample container for instrument measurement. This is heated at a test temperature of 70 ° C. and an air atmosphere at a rate of 10 ° C./min. The rise of the exothermic peak observed when the polymerization of the acrylic acid aqueous solution starts is observed and recorded, and the time until the exothermic peak appears is taken as the induction time. It shows that there exists an effect of a polymerization inhibitor, so that induction time is long. The results of the polymerization inhibition test are shown in FIG. In addition, the thing which does not use a polymerization inhibitor as a control (blank) was used for the test.

  From the above results, the above five compounds which are representative salicylic acid hydrazides or derivatives thereof according to the present invention are equivalent to or longer than the methylhydroquinone or p-methoxyphenol used as a comparative example. showed that. Specifically, at the test temperature of 70 ° C., a remarkable polymerization suppression effect of 85 minutes or more was obtained in the compound 1 according to the present invention. About the compound 2 and the compound 3, the polymerization inhibitory effect equivalent to 80 minutes or more equivalent to the methoxyphenol which is a normally used polymerization inhibitor was acquired, and it was judged that it was practical. In addition, Compound 4 and Compound 5 gave a longer induction time than methylhydroquinone.

  The salicylic acid hydrazide or derivative thereof used in the present invention can also be used as an aldehyde treating agent in the production of acrylic acid to efficiently separate acrylic acid and aldehydes as by-products. Conventionally used aldehyde treating agents have the property of promoting polymerization when added in excess, but the salicylic acid hydrazide or derivative thereof used in the present invention exhibits a polymerization inhibitory effect, so there is no concern about it, aldehyde treatment It is effective as an agent.

(Hue stability test)
Among the representative salicylic acid hydrazides or derivatives thereof according to the present invention, a hue stability test was performed on salicylic acid hydrazide (compound 1) having the highest polymerization inhibitory effect. In many cases, the coloring that occurs during use as a polymerization inhibitor is considered to be caused by the coloring of the additive added thereto. Therefore, it can be said that if an additive which does not easily change over time or is colored by heat is used, a polymer with little coloring can be obtained.

  A NOx treatment test was performed according to the following procedure, and the anti-coloring performance was examined. First, 20 mg of various polymerization inhibitors corresponding to 0.1% by mass of acrylic acid is added to 20 g of a 50% by mass acrylic acid aqueous solution, stoppered, and dissolved in an ultrasonic cleaner. Next, 10 g of the completely dissolved sample solution is weighed into a 30 mL vial and sealed with a rubber cap and an aluminum holder. Using a syringe, 0.1 ml of NOx gas generated by a nitrogen oxide gas generator in accordance with JIS L0855 (Test method for dyeing fastness to nitric oxide gas) is taken and injected into a vial containing sample liquid, and shaken well. Mix NOx gas and sample solution. The sample is allowed to stand at room temperature for 1 hour and then compared with a standard solution using a Gardner colorimeter to determine the number of colors. This is compared with the Gardner number of the sample before the NOx treatment, and the change amount Δ is obtained. The results are shown in Table 2. The number of colors by the Gardner colorimeter used in this test example conformed to JIS K-0071-2.

  From the above results, the salicylic acid hydrazide (Compound 1) according to the present invention shown in Test Example 1 is more colored than the phenolic polymerization inhibitors represented by Hydroquinone and p-methoxyphenol in Test Examples 2 and 3. Since the degree is extremely small, an excellent effect can be expected in a field where a polymer having high hue stability is required.

Next, the five compounds of the above compounds 1-5 is a salicylic acid hydrazide or a derivative thereof, as a comparative example, 4,4'-dicumyl diphenylamine (DCD), 2,6-di -t- butyl hydroxy toluene (BHT) was used to test the antioxidant effect of mineral oil. As a control (blank), the case where no antioxidant was used was also used for the test.

(Antioxidation effect test)
A mineral oil composition comprising 0.2% by mass of the above compound and 99.8% by mass of 150 neutral oil was subjected to JIS K2514 Rotating Cylinder Type Oxidation Stability Test (RBOT), and the results of the obtained oxygen absorption induction time were shown. It was shown in 2. The test temperature was 150 ° C. The oxygen absorption induction time is measured as a measure of oxidative stability, and the longer the time, the better the oxidative stability. In addition, what consists only of 150 neutral oil was also used for the test as a control (blank) . Both salicylic acid hydrazide, or five compounds which are derivatives thereof were found to have an antioxidant effect. Compound 1 of the salicylic acid hydrazide or a derivative thereof in particular, antioxidant effect with Compound 2 and Compound 4 was remarkable. In the compound 3 and the compound 5, the antioxidant effect was acquired compared with the blank which does not add antioxidant.

  In the method using the salicylic acid hydrazide or derivative thereof according to the present invention as a polymerization inhibitor, it is suitable for use in applications where the use of a colored base material is not preferred because it is difficult to cause color change due to aging or heat. . Moreover, since it is excellent in water solubility, it can be expected to reduce the burden on the environment. Further, it can be suitably used for the purpose of preventing oxidation of lubricating oil.

It is a graph which shows the result of a polymerization inhibition test. It is a graph which shows the result of an antioxidant effect test.

Claims (8)

Following formula

(In formula (1), Z is represented by —NHR ₁ or —N═CR ₂ R ₃ , and any of R ₁ , R ₂ , and R ₃ may be branched with hydrogen or C 1-6. Represents a saturated alkyl group)
The polymerization suppression method which adds the salicylic acid hydrazide represented by these, or its derivative (s) with respect to the monomer which is (meth) acrylic acid, its ester, or its salt, or its partial polymer at 5-1000 ppm. In the salicylic acid hydrazide represented by the formula (1) or a derivative thereof, R ₁ in the formula is hydrogen or a saturated alkyl group having 1 to 6 carbon atoms which may be branched, and either R ₂ or R ₃ The method for inhibiting polymerization according to claim 1, wherein is a methyl group and the other is a saturated alkyl group having 1 to 4 carbon atoms which may be branched. The salicylic acid hydrazide or a derivative thereof, salicylic acid hydrazide, N '- (1-methylethylidene) salicylic acid hydrazide, N' - (1-isobutyl-ethylidene) salicylic acid hydrazide, N '- (1-methylethyl) salicylate hydrazide, and N' The method for inhibiting polymerization according to claim 1, which is at least one selected from the group consisting of-(1-isobutylethyl) salicylic acid hydrazide. The said salicylic acid hydrazide or its derivative (s) is added in 10-500 ppm with respect to the monomer which is (meth) acrylic acid, its ester, or its salt, or its partial polymer, The any one of Claims 1-3. The polymerization inhibiting method according to 1. Following formula

(In formula (1), Z is represented by —NHR ₁ or —N═CR ₂ R ₃ , and any of R ₁ , R ₂ , and R ₃ may be branched with hydrogen or C 1-6. Represents a saturated alkyl group)
Salicylic acid hydrazide represented by
(Meth) acrylic acid, its ester, or a monomer that is a salt thereof or a partial polymer thereof,
The polymerization inhibitor whose content of the said salicylic acid hydrazide or its derivative is 5-1000 ppm with respect to the said monomer or its partial polymer . In the salicylic acid hydrazide represented by the formula (1) or a derivative thereof, R ₁ in the formula is hydrogen or a saturated alkyl group having 1 to 6 carbon atoms which may be branched, and either R ₂ or R ₃ The polymerization inhibitor according to claim 5, wherein is a methyl group and the other is a saturated alkyl group having 1 to 4 carbon atoms which may be branched . The salicylic acid hydrazide or a derivative thereof may be salicylic acid hydrazide, N ′-(1-methylethylidene) salicylic acid hydrazide, N ′-(1-isobutylethylidene) salicylic acid hydrazide, N ′-(1-methylethyl) salicylic acid hydrazide, and N ′. The polymerization inhibitor according to claim 5, which is at least one selected from the group consisting of-(1-isobutylethyl) salicylic acid hydrazide. The polymerization inhibitor according to any one of claims 5 to 7, wherein a content of the salicylic acid hydrazide or a derivative thereof is 10 to 500 ppm with respect to the monomer or a partial polymer thereof.

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